Along with growth of industries related to portable electronic devices associated with developments of semiconductor fabricating technologies and communication technologies and increasing demand for development of an alternative energy based on environmental conservation and resource exhaustion, battery-related techniques are being actively researched. Particularly, secondary batteries that can be recharged and repeatedly used are being researched.
Fields of applications of secondary batteries are expanding from batteries for small devices, such as mobile phones, laptop PCs, and mobile display devices, to mid-sized and large-sized batteries including batteries for electric vehicles and batteries applied to hybrid vehicles. Basically demanded features of such a battery include small weight, small volume, high energy density, excellent charging/discharging speeds, excellent charging/discharging efficiencies, excellent cycle characteristics, high stability, and high economic feasibility.